Cooling therapy for acute stroke

Stroke is a life-threatening event in which part of the brain stops functioning properly, because it either does not receive blood and oxygen or it is damaged by bleeding from a ruptured blood vessel. Interventions to reduce temperature may protect brain tissue from damage during stroke. Previous studies have shown that patients with a lower body temperature at the time of stroke have a better outcome than those with a higher body temperature. To reduce death or disability, temperature-lowering therapy is used in open-heart surgery, after cardiac arrest and in babies who may have suffered from a lack of oxygen at birth. By contrast, the therapeutic effect of temperature-lowering therapy in patients with traumatic brain injury is less promising. Besides its potential beneficial effects, temperature-lowering therapy may have adverse effects including chest infection, venous thrombosis or cardiac arrhythmias. This review aimed to assess the potential benefits and risks of temperature-lowering therapy in patients with acute stroke. All studies that compared the use of physical or pharmacological temperature-lowering therapies on acute stroke with usual medical management in acute stroke patients were considered. Physical temperature-lowering techniques included cooling blankets, cooling fluids, cooling helmets and other devices. Pharmacological temperature-lowering interventions included drugs used to reduce temperature. The results of the five included pharmacological and three physical temperature reduction trials, involving 423 participants with acute stroke, do not indicate a clinical benefit or harm. Both interventions were associated with a slight increase in the occurrence of infections, but this was not statistically significant. A clinically significant effect of temperature-lowering therapy on outcome after stroke was not demonstrated, but cannot be ruled out. Large clinical trials are therefore needed to assess the effect of temperature-lowering therapies in acute stroke.

Authors' conclusions: 

There is currently no evidence from randomised trials to support routine use of physical or pharmacological strategies to reduce temperature in patients with acute stroke. Large randomised clinical trials are needed to study the effect of such strategies.

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Background: 

Increased body temperatures are common in patients with acute stroke and are associated with poor outcome. In animal models of focal cerebral ischaemia, temperature-lowering therapy reduces infarct volume. In patients with acute stroke, lowering temperature may therefore improve outcome. This is an update of a Cochrane review first published in 1999.

Objectives: 

To assess the effects of pharmacological and physical strategies to reduce body or brain temperature in patients with acute stroke.

Search strategy: 

We searched the Cochrane Stroke Group trials register (last searched December 2007). In addition, we searched MEDLINE and EMBASE (January 1998 to December 2007). We scanned references and contacted authors of included trials. For the previous version of this review, the authors contacted pharmaceutical companies and manufactures of cooling equipment in this field.

Selection criteria: 

We considered all completed randomised or non-randomised controlled clinical trials, published or unpublished, where pharmacological or physical strategies or both to reduce temperature were applied in patients with acute ischaemic stroke or intracerebral haemorrhage. Outcome measures were death or dependency (modified Rankin Scale score ≥ 3) at the end of follow up, and adverse effects.

Data collection and analysis: 

Two review authors independently applied the inclusion criteria, assessed trial quality, and extracted and cross-checked the data.

Main results: 

We included five pharmacological temperature reduction trials and three physical cooling trials involving a total of 423 participants. We found no statistically significant effect of pharmacological or physical temperature-lowering therapy in reducing the risk of death or dependency (odds ratio (OR) 0.9, 95% confidence interval (CI) 0.6 to 1.4) or death (OR 0.9, 95% CI 0.5 to 1.5). Both interventions were associated with a non-significant increase in the occurrence of infections.

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